We’ve enjoyed the sun’s warming power ever since Maui and his brothers beat it into submission all those years ago, but only during the day. Infrared (IR) panel heaters are touted as a way to recreate this toasty solar warmth long after the sun has dipped below the horizon. We tested IR panels against electric fan, radiant and oil-column heaters to see if they can recreate the sensation of a warm summer day on a chilly winter evening.
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Typical portable electric heaters, such as oscillating fans and oil columns, use convective heating to warm a room. However, hot air rises, which results in the room tending to heat from the ceiling down, leading to a warm head and cold feet.
IR heaters don’t heat air directly. They emit infrared radiation that heats objects in the room, similar to how the sun warms things by shining on them.
The objects then radiate heat back into the room. In theory, this means an IR heater can be set to a lower temperature than other forms of convective heating.
Manufacturers claim IR panels are cheaper to run than heat pumps, with some marketing material touting power savings of upwards of 33%. It’s a bold claim. Heat pumps put out more than three times the warmth of their conventional electric counterparts for the same power use.
What about skin cancer and other damaging effects of sunlight? Don’t be alarmed by an IR heater’s sunshine-creating wizardry. It only outputs heat-producing infrared wavelengths, not the harmful ultraviolet parts of the electromagnetic spectrum.
We tested IR panels against electric fan, radiant and oil-column heaters in our thermal performance lab.
To account for the radiant effect from an infrared heater, we assessed the thermal comfort each heater produced. We wanted to find if it would leave you feeling warm and comfortable, not just if it heated the air in the room effectively.
Thermal comfort is different for everyone. We all know someone who pulls on a jersey when everybody else is in summer clothing, or that one bloke who wears stubbies year-round.
Some factors affecting your thermal comfort are independent of the heat source: how active you are, what you’re wearing, and the humidity.
Our test isolated the factors caused by the heat source: air temperature, the temperature difference from head to toe, air movement caused by the heater, and the level of radiant heating. Our thermal comfort rating is derived from these results.
We purchased two 450W IC Series panels from infraredpanels.co.nz ($499 per panel). The panel size was based on recommendations taken from the supplier’s website for our 17m² test room. This is considerably less than half the maximum output of a 2000-2400W electric heater, often used in a room of that size. We didn’t use a thermostat, so the IR panels used their combined 900W output. We ran the other heaters on their lowest power settings – a similar output to the IR panels.
We mounted the IR panels on opposite walls first and then together on the ceiling. The other heaters were positioned at one end of the test room. Sensors were set up to simulate someone sitting in the middle of the room.
The IR panels we tested produced an excellent thermal comfort and there wasn’t much difference between mounting them on the wall or ceiling. However, the radiant and fan heater types were just as good.
|Heater type||Thermal comfort||Radiant heat (°C)||Temperature difference (°C)||Air temperature (°C)||Power consumption (W)|
|IR panels - wall mounted||Excellent||0.64||0.86||22.0||813|
|IR panels - ceiling mounted||Excellent||0.75||1.24||21.6||937|
|Oil column||Very good||-0.08||1.74||20.1||640|
GUIDE TO THE TABLE Thermal comfort is rated based on radiant heat, temperature difference and air temperature. Radiant heat is a measure of the temperature of radiant heat falling on a person minus the air temperature. Temperature difference is the change in temperature from the head to feet. Air temperature is the measured air temperature at the mid-point of the test room. Power consumption is the power used by each heater during the test.
In our test, IR panels put out the most radiant heat. You only feel this as warmth when the power of the radiant heat falling on your skin exceeds the air temperature. Fan heaters deliver warm, moving air, which doesn’t have this radiant effect, but rather has a chilling effect on the skin, like the feeling of a southerly breeze on a warm summer day. This is why the fan heater received a negative score.
Temperature difference relates to the heat distribution where our “person” was sitting. The greater the difference in temperature between your head and your feet, the less comfortable you feel. The IR panels delivered the lowest temperature difference, but the fan heater would have left your feet 3.5°C cooler than your head.
We found you can overcome a lack of radiant heat and still get excellent thermal comfort by focusing on increasing the air temperature instead. The fan heater worked to its strengths and raised the air temperature to nearly 24°C, which would leave most people feeling toasty.
Our power consumption test found IR panels didn’t save power compared to the other electric heaters. It should be noted the conventional heaters were run at their lowest settings and could be ramped up, whereas IR panels have no power settings – they are either on or off. If you found they struggled to warm your room, your only option would be to either add more panels or turn on another heat source.
IR heaters come at a hefty price. Fitting out our thermal lab with two 450W panels cost nearly a grand. You could pick up a similarly performing radiant heater for less than $100.
To get the radiant heat effect, you need to be in line-of-sight of the IR panel. They’re no good mounted around a corner. Mounting them opposite windows is also a waste of energy as the heat passes straight through the glass – akin to running a fan heater with the front door open. You can avoid this by mounting them on the ceiling.
All heaters work more efficiently when used with a thermostat to monitor room temperature. IR panels are no different. A thermostat can control multiple panels and, though it comes at an extra cost, it means the panels won’t be running the whole time they are plugged in.
These images show the heat distribution of the air in our test lab created by each heater. Each image is a slice through the centre of the room. A uniform spread of the same colour over the entire area shows an even heat. The IR panels and radiant heater created an evenly distributed heat, but the radiant heater struggled to heat the far end of the room. The fan heater shot out a stream of hot air that rose quickly to the ceiling, whereas the oil-column heated the air directly above it. You can see how these convective heaters might leave a person needing a pair of slippers to keep their feet warm.
Wall-mounted IR panels
Oil column heater
We are still investigating the performance of our IR panels. Next time, we want to include a heat pump for comparison and look deeper into thermal comfort, room heat-up time and power use. We’ll get the results online as soon as we can.
By James le Page